This specification refers to an invention patent concerning a sensor for the automatic and accurate determination, through a rigorous procedure, of the vector that defines the incident energy flux density, under different formsxe2x80x94for example, optical or thermalxe2x80x94originated from any direction in the space.
This invention is related to sector of intelligent sensors.
Its field of application is in intelligent interfaces for information systems, robotics, industrial automation, man-machine interfaces, as well as in the real pointing devices, of great interest in the area of disable and elderly peoplexe2x80x94tetraplegics, blinds . . . xe2x80x94being able to be integrated on input devices, for example free-hands mouse.
A further field of application is in automatic systems for the patients study with mobility difficulties, for example in the automatic record and analysis of their movements, as well as the field of the rehabilitation of this type of patients: paraplegics, tetraplegics, persons with arthritis, multiple sclerosis, cerebral paralysis.
Another field of application is that of input devices for virtual reality system.
There are well known systems that use the directional character of the phenomenon of energy radiation through waves, for example luminous radiation or infrared radiation, to build devices that permit, in a way more or less rudimentary, the determination of the direction of the device with respect to the arrival direction of the energy.
The systems known do not constitute concepts that permit to change, in a rigorous manner, the set of the possible values of the incident radiation in other set of electrical signals that express accurately the intensity and arrival direction of the radiation. That is to say that the intensity and direction information that is intended to know is degenerated by the own concept in the sensing process.
The document patent WO 9519577 A, published on the Jul. 20, 1995 describe a method for monitoring the position of an article in space. It permits to obtain a relative precision, as indicated in the cited document, but it is not a rigorous and accurate method for many applications.
There are also other methods related in the patent documents: U.S. Pat. No. 5,367,315 A, published the Nov. 22, 1994; U.S. Pat. No. 5,187,540 A, published the Feb. 16, 1993; FR 2447017 A, published Aug. 14, 1980 and GB 2284478 A, published Jun. 7, 1995. None of this describes a method that permit, in a practical and rigorous way, to realise the object of the vectorial photosensor: to measure in an accurately way the intensity and arrival direction of an optical radiation originated from any direction in the space.
The documents cited as description of the background art, even though solve concrete problems, they do not give a solution to the problem of the rigorous determination of the intensity and arrival direction of a radiation originating from any direction in the space. The solution to this problem, especially in the region of the corresponding electromagnetic spectrum to the near infrared and thermal infrared, is of great interest by the big number of applications that are derived.
This invention constitutes a specific concept that permits to measure accurately the intensity and direction of arrival of an incident energy to the sensor, through a rigorous and automatic procedure.
This sensor, implemented through an undefined number of sensitive means placed not parallel in the space, e.g. on polyhedric surfaces, has a lot of new characteristics in comparison with the sensor systems, known. We have designated it as vectorial photosensor because it permits the transformation of the incident energy, through an appropriate electronic means, in a set of electrical signals that represent, rigorously and accurately, the intensity and direction of the incident energy.
This invention provides a great flexibility in the number and distribution of the sensitive means to the incident energy, permitting to configure any polyhedric surface, constituted by three or more sensitive means, as the input device of the vectorial photosensor.
It is based in the determination of the direction and intensity of the incident energy by means of the measurement of the optical signals received by a set of sensitive means, that transform the incident energy into electrical signals. These sensitive means are located in the space building a polyhedric surface, which incorporates from three up to an undefined number of sensitive means.
The electrical output of the sensitive means, are acquired through an electronic means that transforms the electrical output signals of these sensitive means, that is to say the sensitive facets of the polyhedric surface. The. electronic means also process the acquired outputs signals through a specific algorithm that permits to obtain the components of the vector that characterise the flow density of the incident energy.
The incident energy flux is transformed by the sensitive elements into proportional electrical signals to the energy flux density, to the cosine of the incidence angle, to the effective surface and as well as to the responsivity of each sensitive means.
We designate p to a vector whose module represents the value of the energy flux density, being its direction and sense the same that the propagation of the radiation. We introduced also a new concept, which we designate vectorial responsivity, being its module the product of the responsivity of one of the sensitive means by its sensitive surface and its direction the perpendicular to such surface, being incoming by the sensitive face.
The electrical output of each sensitive means, designated si, can be expressed as the scalar product of the vectorial responsivity ei and the vector p that represents the energy flux density:
si=eixc2x7p
This invention may incorporate from three up to an undefined number N of sensitive means, located each one of them on each one of the faces of a polyhedric surface, constituting the transducer of the vectorial photosensor.
For three sensitive means the electrical output signals are:
s1=e1xc2x7p s2=e2xc2x7p s3=e3xc2x7p
Considering an orthogonal base OXYZ, we represent the vectorial responsivities in function of its components with respect to the base as:                               e          1                =                  [                                                                      e                                      1                    ⁢                    x                                                                                                                        e                                      1                    ⁢                    y                                                                                                                        e                                      1                    ⁢                    z                                                                                ]                                              e          2                =                  [                                                                      e                                      2                    ⁢                    x                                                                                                                        e                                      2                    ⁢                    y                                                                                                                        e                                      2                    ⁢                    z                                                                                ]                                              e          3                =                  [                                                                      e                                      3                    ⁢                    x                                                                                                                        e                                      3                    ⁢                    y                                                                                                                        e                                      3                    ⁢                    z                                                                                ]                    
In an analogous way we represent the energy flux density in function of its components with respect to the base as:   p  =      [                                        p            x                                                            p            y                                                            p            z                                ]  
In this way we represent the signals generated by the sensitive means as:       s    i    =                    [                                                            e                ix                                                                                        e                iy                                                                                        e                iz                                                    ]            t        ·          [                                                  p              x                                                                          p              y                                                                          p              z                                          ]      
that is to say:       s    i    =                                          [                          e              ix                                                            e            iy                                                              e              iz                        ]                                ·          [                                                  p              x                                                                          p              y                                                                          p              z                                          ]      
The equation that describes the physical implementation of this invention is:       [                                        s            1                                                            s            2                                                            s            3                                ]    =            [                                                  e                              1                ⁢                x                                                                        e                              1                ⁢                y                                                                        e                              1                ⁢                z                                                                                        e                              2                ⁢                x                                                                        e                              2                ⁢                y                                                                        e                              2                ⁢                z                                                                                        e                              3                ⁢                x                                                                        e                              3                ⁢                y                                                                        e                              3                ⁢                z                                                        ]        ·          [                                                  p              x                                                                          p              y                                                                          p              z                                          ]      
that is to say:
[si]=[eij]xc2x7[pj]
The matrix, whose rows represent the vectorial responsivities of the photosensing polyhedric structure built by the sensitive means, constitutes a new concept which we designate vectorial responsivity matrix.
The vectorial responsivity matrix characterizes the electrical response of the polyhedric surface to the incident energy, and constitutes the transducer of the invention: the vectorial photosensor.
The determination of the components of the vector p, that defines the incident energy flux density, is obtained through the implementation of a specific algorithm that processxe2x80x94by an appropriate electronic meansxe2x80x94the electrical output signals of the sensitive means of the polyhedric surface.
Once the values of the signals generated by the polyhedric surface are acquired through an appropriate electronic means, and knowing the vectorial responsivity matrix, whose elements are stocked in the memory of the electronic means, is obtained the vector that represents the energy flux density through the specific algorithm implemented by the electronic means.
Many mathematical methods get to obtain the vector p from the above equation that describes physically the implementation of the vectorial photosensor and constitute a fundamental characteristic of this invention.
The elements of the vectorial responsivity matrix are characteristic parameters of the vectorial photosensor. The value of these elements depends of the characteristics of the sensitive means and of its place in the space, that is to say depends of the responsivities of the sensitive means and of the geometric form of the polyhedric surface implemented.
A way to obtain the vector p from the vectorial photosensor equation is by implementing the algorithm:
[pj]=[eij]xe2x88x921xc2x7[sj]
The value of the module of the vector p represents the value of the energy flux density from a source at the plyhedric surface and, consequently, it is possible to calculate the distance to the source when the radiant intensity is known and the atmospheric absorption is small.
If the sensitive means are placed in the space in an orthogonal way, we establish, an orthonormal base OXYZ, with its axes perpendicular to the active surface of each photosensor.
The electrical signals to the output of each photosensor, that we will designate si are the following scalar products:
sx=exxc2x7p syeyxc2x7p sz=ezxc2x7p
that is to say:
sx=exp cos xcex1 sy=eyp cos xcex2sz=ezp cos xcex3
Dividing each signal by the mode of the vectoal responsivity of each photosensor we have the normalised signals:
xe2x80x83sxe2x80x2x=sx/ex=p cos xcex1
sxe2x80x2y=sy/ey=p cos xcex2
sxe2x80x2z=sz/ez=p cos xcex3
The unitary vector uxe2x80x94that it defines the arrival direction of the emission with respect to the reference systemxe2x80x94is determined by a expression that depends of the normalised signals, and it is invariant respect to the value of the radiation and consequently invariant also with respect to the distance to the emitter. The unitary vector is:
u=cos xcex1i+cos xcex2j+cos xcex3k
cos xcex1=sxe2x80x2x/p cos xcex2=sxe2x80x2y/p cos xcex3=szxe2x80x2/p
it permits to write:
(sxe2x80x2x/p)2+(sxe2x80x2y/p)2+(szxe2x80x2/p)2=cos2xcex1+cos2xcex2+cos2xcex3=1
that is to say:
p=(sxe2x80x2x2+sxe2x80x2y2+sxe2x80x2z2){fraction (1/2+L )}
determining the unitary vector, that defines the direction of the radiation, by the expression:
u=(sxe2x80x2x/(sxe2x80x2x2+sxe2x80x2y2+sxe2x80x2z2)xc2xd)i+(sxe2x80x2y/(sxe2x80x2x2+sxe2x80x2y 2+sxe2x80x2z 2)xc2xd)j+(sxe2x80x2z/(sxe2x80x2x2+sxe2x80x2y2+sxe2x80x2z2)xc2xd)k
The vectorial photosensor, in one of its applications, includes a energy radiating means, firm to a reference system Oxe2x80x2Xxe2x80x2Yxe2x80x2Zxe2x80x2 fixed in the space, that illuminates at least three of the sensitive means, fixed to other reference system OXYZ, whose origin O is fixed in the space. This application permits to obtain accurately the orentation of the sensitive means in the space, that is to say the orientation of the system OXYZ.
The vectorial photosensor includes, in one of its applications, an electronic means of pulsated energy emissions. The acquisition of electrical output signals of each one of the sensitive means is synchronized with this pulsated emission.